With the greatly increased use of word processors and personal computer terminals having CRT displays in both the workplace and home, the problem of reflection and glare has become acute. Such reflection and glare, now represents one of the major objections and problems associated with long and continuous use of CRT type and other visual display. Although the problem has existed for years with television and other CRT displays, extremely long term continuous viewing was not generally required. A television viewer seldom if ever, is required to read fine print from close range and is able to shift his head positions or move his entire body to a different viewing location in the room to avoid reflections or glare on the television screen. Unfortunately, with respect to computer and word processor terminals and the like, the operator must maintain eyepoint within a relatively limited range of positions, usually within arms length, since he or she must be within reading distance of the relatively small characters on the screen and may also be required to refer to other written input data sources and/or a keyboard which is located proximate the visual display. Consequently, freedom of head motion so as to find a location where reflections and glare from the CRT screen are not objectionable may not be possible without considerable muscle strain. The basic concept of such glare and reflection reduction used by the present invention was first disclosed in U.S. Pat. No. 4,032,222 issued to J. M. Lapeyre. As disclosed in that patent, the natural and still common practice of orienting the display plane of a visual display at right angles with the line of sight from an observer's eyepoint may represent the worst possible orientation for such a light emitting display. As is further disclosed in that patent, glare can be eliminated by proper orientation of the display plane of the visual display in combination with the use of a light obstructing shield. As disclosed in the aforementioned Lapeyre patent, the inventive concept may be used with many and varied light emitting displays. In addition, U.S. Pat. No. 4,235,523 also to Lapeyre discloses and claims a very important use of the original concept as it applies to traffic signals. It will of course be appreciated that traffic signals being located outdoors are subjected to extreme glare and are particularly subjected to glare from the sun. Other patents considered relevant to the basic concept during the prosecution of of the U.S. Pat. No. 4,032,222 include U.S. Pat. Nos. 2,162,791 to Shreve; 2,819,459 to Dodd; 3,499,112 to Heilmeir, et al; 3,531,178 to Wirth; 3,566,602 to Bergey, et al; and 3,881,805 to Hosokawa, et al. In addition, various electronic arcade games and pocket-size portable television receivers incorporate the basic concept of the original Lapeyre U.S. Pat. No. 4,032,222. However, to this date, the applicants are not aware of any CRT terminal with a display and cabinet capable of eliminating visible reflections and glare without requiring a modified desk top to allow the neck of the CRT to be recessed.
Therefore, it is an object of the present invention to provide a desk top visual display system whereby visible reflection and glare is eliminated with respect to a limited but adequate range of eyepoints called the nominal eyepoint.
A further object if to provide a glare-free desk top terminal which requires no angular adjustment for use by various persons during the course of the workday.
It is another object of the present invention to provide a desk top computer terminal display system which operates in conjunction with an input keyboard to eliminate glare and reflection and minimize necessary eye movement between the keyboard and the display.
A further object of the invention is to provide a desk top terminal which has an enhanced contract ratio and consequently may be read at lower electromagnetic radiation levels.
A further object is to provide a desk top unit without glare and visible reflections which is positionable at the proper focal distance for the reading of displayed text.